SEGMENTED PHOTODIODE
In one embodiment of the present invention, the segmented photodiode includes a p type substrate, a p type epitaxial layer formed on the p type substrate, an n type epitaxial layer formed on the p type epitaxial layer, and p type segmenting region provided in the n type epitaxial layer separately from the p type epitaxial layer and segmenting the photosensitive region, and is configured that a depleted layer (first depleted layer) created in an n type region right under the segmenting section located between the p type segmenting region and the p type epitaxial layer by applying a reverse bias voltage is configured to reach a depleted layer (second depleted layer) formed in a junction surface between the n type epitaxial layer and the p type epitaxial layer so that the photosensitive region is electrically isolated.
1 . A segmented photodiode having a photosensitive region being capable of receiving light, said photosensitive region being two-dimensionally segmented into multiple areas, comprising:
a substrate of a first type conductivity;
a first semiconductor layer of the first type conductivity and formed on said substrate;
a second semiconductor layer of a second type conductivity formed on said first semiconductor layer; and
a segmenting section of first type conductivity, provided in said second semiconductor layer spaced apart from said first semiconductor layer providing segmentation of said photosensitive region,
wherein a first depleted layer is formed between said segmenting section and said first semiconductor layer by applying a reverse bias voltage, and
wherein said first depleted layer is configured to reach a second depleted layer formed in a junction surface between said second semiconductor layer and said first semiconductor layer so that said photosensitive region is electrically isolated.
2 . The segmented photodiode as set forth in claim 1 , wherein said segmenting section is composed of a first diffusion layer containing impurity of the first type conductivity diffused therein.
3 . The segmented photodiode as set forth in claim 2 , further comprising a separating unit of the first type conductivity surrounding said photosensitive region that is two-dimensionally segmented, wherein said separating unit is provided over a surface of said first semiconductor layer and a surface of said second semiconductor layer.
4 . The segmented photodiode as set forth in claim 3 , wherein said separating unit and said substrate constitute a common-anode.
5 . The segmented photodiode as set forth in claim 3 , further comprising a plurality of structural units provided therein, said structural unit being composed of said photosensitive region and said separating unit surrounding said photosensitive region.
6 . The segmented photodiode as set forth in claim 3 ,
wherein said separating unit includes a first diffusion layer of the first type conductivity provided in said second semiconductor layer and containing impurity of first type conductivity diffused therein, and a buried layer of the first type conductivity buried in said second semiconductor layer and said first semiconductor layer, and
wherein said first diffusion layer of the first type conductivity is coupled to said buried layer of the first type conductivity in said separating unit.
7 . The segmented photodiode as set forth in claim 1 , wherein a second diffusion layer of the second type conductivity containing impurity of second type conductivity diffused therein is provided in the surface of said second semiconductor layer.
8 . The segmented photodiode as set forth in claim 1 ,
wherein said photosensitive region is configured of a plurality of small regions electrically isolated by said segmenting section, and
wherein said second depleted layer is formed over the entire area of said photosensitive region.
9 . The segmented photodiode as set forth in claim 1 , wherein said segmenting section is cross-shaped in two-dimensional view, and provides a two-dimensional segmentation of said photosensitive region into four sections.
10 . The segmented photodiode as set forth in claim 3 , wherein a second diffusion layer of the second type conductivity containing impurity of second type conductivity diffused therein is provided in the surface of said second semiconductor layer.
11 . The segmented photodiode as set forth in claim 3 ,
wherein said photosensitive region is configured of a plurality of small regions electrically isolated by said segmenting section, and
wherein said second depleted layer is formed over the entire area of said photosensitive region.
12 . The segmented photodiode as set forth in claim 3 , wherein said segmenting section is cross-shaped in two-dimensional view, and provides a two-dimensional segmentation of said photosensitive region into four sections.